Welded dual chamber impingement tube

ABSTRACT

A tube for being installed into a guide vane of a turbine is provided herein. The tube includes a tube wall for forming a fluid channel and a dividing wall which is arranged inside the fluid channel. The dividing wall includes a first edge and a second edge which is spaced apart from the first edge. The first edge is fixed to a first surface section of the tube wall. The dividing wall is formed in such a way that the second edge resiliently abuts in a detachable manner against a second surface section of the tube wall such that the dividing wall divides the fluid channel in a first channel (I) and a second channel (II).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of International ApplicationNo. PCT/EP2013/067442 filed Aug. 22, 2013, and claims the benefitthereof. The International Application claims the benefit of EuropeanApplication No. EP12183096 filed Sep. 5, 2012. All of the applicationsare incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates to a tube for being installed into a guidevane of a turbine, a guide vane device of a turbine and a method ofmanufacturing a tube for a guide vane of a turbine.

ART BACKGROUND

A turbine nozzle guide vane may include an internal impingement coolingsystem into which cooling air is fed through a tube which is mounted ina vane body of the guide vane. The tube includes holes to directdiscrete flows of cooling air against an internal wall of the guidevane. The tube is typically fixed in a close-fit manner within the bodyof the guide vane in order to restrict radial leakage flows of thecooling air. In order to achieve the close-fit fixation of the tubewithin the guide vane, the tube may be partially flexible in order toprovide a good manufacturing variability.

Furthermore, it is known to split the tube into separate chambers alonga tube's length, whereby each chamber is fed separately with cooling airfrom different sources within the turbine. Such a configuration mayenable a selection of cooling air to optimize the cooling effectivenessover the vane airfoil surface. In order to generate these separatechambers, dividers or bulk head features are incorporated into the tube.The dividers affect the stiffness of the tube, such that the stiffnessof the tube is increased by the dividers. The increased stiffness of thetube leads to a difficult assembly due to fouling or generating theclose-fit between the tube and the guide vane body.

The divider may be brazed to the surfaces of the tube. Hence, duringassembly of the tube, the higher stiffness of the tube due to thedivider may cause a fracture of the brazing connection between thedivider and the tube surface.

U.S. Pat. No. 4,252,501 discloses a hollow cooled vane for a gas turbineengine which comprises at least two apertured members each mountedspaced from a separate part of a vane interior surface. The first ofthese members is provided with the supply of cooling air which passesthrough the apertures in the form of jets to impingement cool therespective first surface. Furthermore, an interconnecting passage isprovided to take the cooling air to a second apertured member where animpingement cools the respective second surface.

U.S. Pat. No. 5,516,260 A discloses a bonded turbine airfoil withfloating wall cooling insert. The airfoil comprises an internal cavitywhich is split by a forward wall and by an after wall.

U.S. Pat. No. 5,259,730 A discloses an impingement cooled airfoil with abonding foil insert. Inside an inner cavity of the airfoil ribs areinserted in order to provide several cavities inside an inner volume ofthe guide vane.

U.S. Pat. No. 2,873,944 comprises a turbine blade cooling. Inside aninner volume of a blade metal sheets are fixed in order to form passagesfor the cooling fluid inside the inner volume of the blade.

SUMMARY OF THE INVENTION

It may be an objective of the present invention to provide a guide vanefor a turbine which is robust and simple to manufacture.

This objective may be solved by a tube for being installed into a guidevane of a turbine, by a guide vane device of a turbine and by a methodof manufacturing a tube for a guide vane of a turbine according to theindependent claims.

According to a first aspect of the present invention, a tube for beinginstalled into a guide vane of a turbine is presented. The tubecomprises a tube wall for forming a fluid channel and a dividing wallwhich is arranged inside the fluid channel. The dividing wall comprisesa first edge and a second edge which is spaced apart from the firstedge. The first edge is fixed to a first surface section of the tubewall. The dividing wall is formed in such a way that the second edgeresiliently abuts in a detachable manner against a second surfacesection of the tube wall such that the dividing wall divides the fluidchannel into a first channel and a second channel.

Furthermore, according to a further aspect of the present invention, aguide vane device of a turbine is presented. The guide vane devicecomprises the above-described tube and the guide vane which comprises aninner volume. The tube is arranged inside the inner volume.

Furthermore, according to a further aspect of the present invention, amethod of manufacturing a tube for a guide vane of a turbine ispresented. According to a method, a tube which comprises a tube wall forforming a fluid channel is pro-vided. A first edge of a dividing wall isfixed to a first surface section of the tube wall. A second edge of thedividing wall, which second edge is spaced from the first edge, isresiliently abutted in a detachable manner against the tube wall suchthat the dividing wall divides the fluid channel into a first channeland a second channel.

The guide vane comprises an aerodynamic profile and guides a hot workinggas of the turbine in a desired direction. The guide vane is mounted toa turbine housing, and in particular to a guide vane carrier. The guidevane comprises a centre axis (e.g. the symmetry axis) which runsgenerally along the length of the guide vane and particularly along aradial direction to a rotary axis of a turbine shaft of the turbine. Theguide vane comprises an inner volume into which the tube is mountable.

The tube comprises the fluid channel, through which cooling fluid (e.g.cooling air) flows. Hence, the tube wall of the tube is cooled by thecooling air such that also the guide vane is cooled by the cooling air.Additionally, the tube wall may comprise holes through which the coolingfluid may flow from the fluid channel to an inner surface of the guidevane for cooling purposes.

The tube and in particular the fluid channel comprises a centre axiswhich runs along the length of the tube and generally parallel to thecentre axis of the guide vane. The fluid channel comprises a fluid inletand a fluid outlet, wherein the fluid outlet is located at an oppositeend of the tube along the central axis with respect to the fluid inlet.In particular, the fluid inlet and the fluid outlet are arranged atopposite ends of the tube in such a way that the cooling fluid flowsthrough the fluid channel along a radial direction with respect to therotary axis of the turbine shaft.

The guide vane comprises a leading edge against which the hot workinggas of the turbine streams and a trailing edge, where the hot workinggas streams away from the guide vane. Hence, the hot working gas heatsthe section of the guide vane in the vicinity of the leading edge morethan the section of the guide vane in the vicinity of the trailing edge.Hence, in order to provide a more efficient cooling of the guide vane,it is desired to provide a cooler cooling fluid or a higher mass flow ofthe cooling fluid in the vicinity of the leading edge than in thevicinity of the trailing edge.

For this reason the fluid channel of the tube is divided by the dividingwall into a first channel and a second channel. The first channel andthe second channel are divided by the dividing wall in such a way thatthrough the first channel a cooling fluid with different parameters(temperature, mass flow, pressure) in comparison to parameters of acooling fluid which flows through the second channel is provided.

Alternatively, also two or a plurality of dividing walls may be arrangedinside the fluid channel in order to provide a respective plurality offurther channels inside the fluid channel.

The dividing wall may be a sheet metal and a metal plate, respectively,which divides the fluid channel into the first channel and the secondchannel. The dividing wall runs generally along the length of the tube.According to the present invention, the dividing wall is fixed with afirst edge to a first surface section of the tube wall and abuts with asecond edge against a second surface section of the tube wall.

The first edge and the second edge may be for example parallel edges ofthe dividing wall, wherein the first edge and the second edge areopposite located edges of the dividing wall. The first edge is a freeend of the plate. The first edge has a longitudinal extension and is inother words a free end of one side of the dividing wall. Accordingly,the second edge has a similar longitudinal extension and is in otherwords a free end of another side of the dividing wall, i.e. oppositewith respect to the first edge. The dividing wall may have a rectangularshape, wherein the edges and thus the dividing wall run along the lengthand the centre axis of the tube, respectively. Alternatively, thedividing wall may also comprise a curved shape. In particular, thedividing wall may run from a first fluid opening of the fluid channel toa second fluid opening of the fluid channel. Accordingly, each of thefirst channel and the second channel, which are formed by the dividingwall, may have a respective first fluid opening and a respective secondfluid inlet. Through each of the respective first and second channels,fluid with different parameters may be injected.

The term “resiliently abuts in a detachable manner” means that thesecond edge is not fixed to the second surface section by any fixationmeans (such as welding, brazing or gluing means) but only (i.e.sealingly) contacts the second surface section. In particular, thecontour of the second edge in comparison to the second surface sectionis formed and adapted in such a way that a sealing between the firstchannel and the second channel is achievable. Furthermore, the contactof the second edge to the tube wall (i.e. the second surface section) isstrong enough, such that the sealing between the first channel and thesecond channel is provided. The dividing wall may be a metal plate andhence elastically deformable and hence comprises resilient properties.

Hence, if the first channel is located more upstream with respect to aflow direction of the hot working gas of the turbine and hence in thevicinity of the leading edge of the guide vane, more cooling fluid or acooler cooling fluid may be injected such that the cooling efficiency ofthe cooling fluid in the first channel is higher than a cooling fluidwhich is injected through the second channel, wherein the second channelis located closer to the vicinity of the trailing edge of the guidevane.

By the present invention, the dividing wall is (only) fixed with thefirst edge to the tube wall of the tube. The opposite second edge onlyresiliently abuts in a detachable manner against a second surfacesection of the tube wall. Hence, if the tube is compressed during theinserting of the tube into the inner volume of the guide vane, thesecond edge may slide along the second surface section. Thus, thestiffness of the dividing wall is reduced and an easier manufacturingand installation of the tube inside the guide vane is achieved.Furthermore, if the tube is fitted into the inner volume of the guidevane, the tube may expand elastically again, such that the second edgeslides along the second surface section into its initial position.However, during the compression and expansion of the tube, the secondedge stays in contact and is kept abutted against the second surfacesuch that a sealing between the first channel and the second channel isprovided.

Hence, by the present invention, a compressible and expend-able tube fora guide vane is generated without complex manufacturing methods. Inorder to provide the above-described inventive tube with the firstchannel and the second channel, only one fixing fabricating step forfixing the dividing wall to the tube wall is necessary, namely thefixing of the first edge to the first surface section of the tube wall.

According to a further exemplary embodiment, the first edge is brazed,welded or glued to the first surface section of the tube wall.

According to a further exemplary embodiment, the dividing wall isarranged inside the fluid channel in such a way that, if a first fluidpressure in the first channel is higher than a second fluid pressure inthe second channel, the second edge is pressed against the tube wall bythe fluid pressure and in particular by the differential pressurebetween the first fluid pressure and the second fluid pressure.

According to a further exemplary embodiment, the first surface sectionhas a first normal, wherein the dividing wall comprises a further firstsurface section which has a further first normal and which comprise thefirst edge. An angle between the normal of the first surface section andthe further normal of the further first surface section differs to 90°.In particular, the dividing wall runs from the first edge notperpendicular with respect to the first normal of first surface sectionof the tube wall. Hence, if a force acting parallel to the first normalof the first surface section (e.g. due to compressing of the tube), theforce presses the dividing wall aside such that the second edge slidesalong the second surface section and the dividing wall does not preventthe compressing of the tube.

The further first surface section may define the complete surface of thedividing wall or may only be a part of the overall surface of thedividing wall. For example, the dividing wall may form an L-shapedcross-section or a U-shaped cross-section, wherein the further firstsurface section defines the section comprising the first edge.

Accordingly, according to a further exemplary embodiment of the presentinvention, the second surface section has a second normal, wherein thedividing wall comprises a further second surface section which comprisesa second edge, wherein the further second surface section has a furthersecond normal. The dividing wall is formed such that a further anglebetween the second normal of the second surface section and the furthersecond normal of the further second surface section differs from 90°.

In particular, the dividing wall runs from the second edge notperpendicular with respect to the second normal of second surfacesection of the tube wall. Hence, if a force acting parallel to thesecond normal of the first surface section (e.g. due to compressing ofthe tube), the force presses the dividing wall aside such that thesecond edge slides along the second surface section and the dividingwall does not prevent the compressing of the tube.

According to a further exemplary embodiment of the present invention,the tube has the above-described centre axis which runs between a firsttube end and a second tube end. The tube is divided along a dividingdirection into a first tube part, i.e. a first tube half, and a secondtube part, i.e. a second tube half. The dividing direction comprises atleast a component which is parallel to the centre axis. Specifically, adividing line between the first tube part and the second tube part runsalong the length of the tube and parallel to the ntre axis of the tube,respectively.

Hence, the first tube part and the second tube part may be fabricatedindependently from each other, wherein after fixing the first tube partwith the second tube part, the tube and respectively the fluid channelare formed.

Furthermore, according to a further exemplary embodiment, the first tubepart and the second tube part are welded, brazed, glued together orjoined together by adding material.

According to a further exemplary embodiment, the first edge of thedividing wall is fixed to the first tube part and wherein the dividingwall is formed in such a way that the second edge resiliently abuts in adetachable manner against the second tube part such that the dividingwall divides the fluid channel into the first channel and the secondchannel. The first edge is fixed to the first tube part in particularbefore the first tube part and the second tube part are fixed together.

Accordingly, according to a further exemplary embodiment of the method,the first edge of the dividing wall is fixed to the first tube part,wherein the first tube part is fixed to the second tube part after thefirst edge has been fixed to the first tube part. The second edge abutsagainst the second tube part.

Hence, before the first tube part and the second tube part are fixedtogether, the dividing wall is fixed with its first edge to the firsttube part. Before the first tube part and the second tube part are fixedtogether, the fixation of the first edge to the first tube part is easybecause the first surface section is easily accessible. By the presentinvention, it is not necessary to apply fixation steps to the dividingwall after the first tube part is fixed to the second tube part, becausea second edge of the dividing wall only resiliently abuts in adetachable manner against the second surface section. That is, thatfurther fixation steps to the dividing wall are not necessary after thefirst tube part is fixed to the second tube part. Hence, it is notnecessary to apply fixation steps to locations of the tube which areonly hardly accessible, such as the second surface section after thefirst tube part is fixed to the second tube part.

Hence, a simplified and easy manufacturing of the above-described tubeis achieved.

Summarizing, by the present invention, a dividing wall is arrangedinside the fluid channel of the tube, wherein only one first edge is(non-detachably) fixed, e.g. by welding, to a first surface section ofthe tube wall. Due to the abutting of the second edge of the dividingwall at the second surface section a fluid channel is dividable into thefirst channel and the second channel although only the first edge is(rig-idly) fixed to the first section of the tube wall.

In particular, the dividing wall, and in particular a further surfacesection comprising the first edge and/or a further surface sectioncomprising the second edge, is angled relatively to the respective firstand second surface section of the tube wall and are thusnon-perpendicular. The dividing wall is only welded to one surface ofthe tube inside the fluid channel, in particular along the tubes length(i.e. along the centre axis) prior to the welding of the second tubepart to the first tube part.

By the present invention, the size of the dividing wall is set andpredetermined in such a way, that a width of the dividing wall betweenthe first surface section and the second surface section of the tube islarge enough such that the second edge resiliently abuts permanentlyagainst the second surface section during operation of the turbine, sothat a reliable separation of the first channel to the second channel bythe dividing wall is achieved.

In particular, the second edge of the turbine is located more upstreami.e. closer to the leading edge of the guide vane in comparison to thefirst edge.

By the above-described tube a simplified manufacturing method for thetube is achieved. The manufacturing method enables the dividing wall tobe attached using a stronger welded joint (as compared to brazing). Byangling the dividing wall with respect to the respective first andsecond normals of the respective first and second surface sections ofthe tube wall and by allowing the second edge to remain free from anypermanently fixing means, this will achieve flexibility of the tube toenable reduced installation forces during installation of the tube intothe guide vane. By setting the length and the size of the dividing walland by welding the first edge at a more downstream location incomparison to the second edge, the dividing wall will ensure a sealbetween the first channel and the second channel. Furthermore, apressure difference between fluid in the first channel and the secondchannel will assist to close and to press the dividing wall against thetube wall.

It has to be noted that embodiments of the invention have been describedwith reference to different subject matters. In particular, someembodiments have been described with reference to apparatus type claimswhereas other embodiments have been described with reference to methodtype claims. However, a person skilled in the art will gather from theabove and the following description that, unless other notified, inaddition to any combination of features belonging to one type of subjectmatter also any combination between features relating to differentsubject matters, in particular between features of the apparatus typeclaims and features of the method type claims is considered as to bedisclosed with this application.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects defined above and further aspects of the present inventionare apparent from the examples of embodiment to be described hereinafterand are explained with reference to the examples of embodiment.Embodiments of the invention will be described in more detailhereinafter with reference to examples of embodiment but to which theinvention is not limited.

FIG. 1 shows a schematical view of a cross-section of the guide vanedevice according to an exemplary embodiment of the present invention;

FIG. 2 shows a perspective view of a guide vane device according to anexemplary embodiment of the present invention as shown in FIG. 1; and

FIG. 3 shows a schematical view of a tube comprising a first tube partand a second tube part according to an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION

The illustrations in the drawings are schematically. It is noted that indifferent figures, similar or identical elements are provided with thesame reference signs.

FIG. 1 shows a guide vane device (i.e. a dual chamber impingement guidevane device) for a turbine, wherein the guide vane device comprises aguide vane 120 and a tube 100. The tube 100 is arranged inside the innervolume 121 of the guide vane 120. The guide vane device may beparticularly of a turbine section of a gas turbine, which will be incontact with a hot working fluid from the outside and particularly alsoin contact with a cooling fluid guided to the interior of the guide vanedevice.

The tube 100 may be installed into the inner volume 121 of the guidevane 120 by a press-fit connection for example. Therefore, the(elastically compressible) tube 100 may be compressed duringinstallation into the inner volume 121 and released after placing thetube 100 into the inner volume 121, such that the tube 100 extends againinto its initial position and such that the press-fit connection betweenthe tube 100 and the guide vane 120 is achieved. Therefore, the tube 100has to provide a low stiffness on the one side but has also to be robustenough on the other side.

The tube 100 comprises a dividing wall 110 which is arranged inside thefluid channel which is housed and surrounded by a tube wall 101 of thetube 100. The dividing wall 110 comprises a first edge 111 and a secondedge 112 which is spaced apart from the first edge 111.

The first edge 111 is fixed to the first surface section of the tubewall 101, e.g. by welding.

The dividing wall 110 is formed in such a way that the second edge 112abuts resiliently abuts against a second surface section of the tubewall 101 such that the dividing wall 110 divides the fluid channel intoa first channel I and a second channel II.

Specifically, the dividing wall 110 comprises a length between the firstedge 111 and the second edge 112, wherein the length is adapted suchthat the second edge 112 is in contact with the second surface section(and hence abuts against the second surface section) when the first edgeis fixed with the first surface section. Furthermore, the dividing wall110 is angled relative to the respective first surface section of thetube wall 101 and/or to the second surface section of the tube wall 101,respectively. In other words, the dividing wall 110 runs between thefirst edge 111 and the second edge 112 non-parallel with respect to afirst normal n1 of the first surface section and/or with respect to asecond normal n2 of the second surface section, respectively. Hence, thedividing wall 110 runs angled relative to the respective surfacesections of the inner surface of the tube wall 101.

In other words, the dividing wall 110 comprises a further first surfacesection which comprises the first edge 111, wherein an angle a betweenthe first normal n1 of the first surface section and the further firstnormal fn1 of the further first surface section differs to 90°.

Accordingly, the dividing wall 110 may comprise a further second surfacesection which comprises the second edge 112, wherein the dividing wall110 is formed such that a further angle f3 between the second normal n2of the second surface section and a further second normal fn2 of thefurther second surface section differs from 90°.

Hence, if the tube 100 is compressed during installation into the innervolume 121 of the guide vane 120, the second edge 112 slides inparticular along the second surface section in an upstream directionwith respect to the flow direction 124 of the working gas of theturbine.

Further, the dividing wall 110 as shown in FIG. 1 is arranged inside thefluid channel in such a way, that if a first fluid pressure pi in thefirst channel I is higher than a second fluid pressure p2 in the secondchannel II, the second edge 112 is pressed against the tube wall 101 bythe first fluid pressure p1, i.e. by the pressure difference between thefirst fluid pressure pl and the second fluid pressure p2.

In particular, the second edge 112 of the dividing wall 110 is locatedcloser to a leading edge 122 of the guide vane 120 and hence moreupstream with respect to the flow direction 124 of the working gas ofthe turbine than the first edge 111 of the dividing wall 110. Generally,in the first channel I, which is located closer to the leading edge 122of the guide vane 120, a higher cooling efficiency is desired and hencea higher fluid pressure pi is generated in comparison to the secondchannel II, which is located more downstream with respect to the flowdirection 124 of the working gas and closer to the trailing edge 123,respectively. Hence, because the first fluid pressure pi is higher thanthe second fluid pressure p2 and because the second edge 112, whichabuts against the second surface section, is located more upstream withrespect to the first edge 111, which is fixed to the first surfacesection, the pressure surplus in the first channel I with respect to thesecond pressure p2 forces and presses the second edge 112 against thesecond surface section of the tube wall 101.

The fluid channel and in particular the first channel I and the secondchannel II comprise a respective fluid inlet and a respective fluidoutlet, such that separated cooling fluids with separated cooling fluidparameters may be injected in each of the channels I, II. In particular,the respective fluid inlets and outlets are located at opposite ends ofthe tube 100 with respect to a centre axis 102 of the tube 100. Thecentre axis 102 runs generally along a radial direction with respect toa turbine shaft of the turbine.

Furthermore, the tube 100 may comprise a first turbine section 103 (i.e.a first turbine half) and a second tube part 104 (second tube half) .The first tube part 103 and the second tube part 104 are divided along adividing line 105, wherein the dividing line runs approximately parallelto the centre axis 102 and along the length of the tube, respectively.Alternatively, the dividing line 105 may only have one component whichis parallel to the centre axis 102. In particular, the dividing line105, 105′ runs from one free end to an oppositely located free end withrespect to the centre axis 102.

FIG. 2 shows the exemplary embodiment shown in FIG. 1 and hencecomprises similar features as already explained above for FIG. 1.

Moreover, in FIG. 2, the first tube end 201 and the second tube end 202is shown. Furthermore, it is shown that the tube wall 101 comprises aplurality of holes 203. The cooling fluid may stream from the firstchannel I and the second channel II into the inner volume 121.Specifically, the cooling fluid streams through the holes 203 andimpinges against the inner surface of the inner wall of the guide vane120. Hence, an impingement cooling is provided.

Furthermore, a dividing direction 204 is shown, along which the tube 100is divided into the first tube part 103 and the second tube part 104.

FIG. 3 shows the tube 100, wherein the tube 100 comprises the first tubepart 103 and the second tube part 104. FIG. 3 shows the tube before thefirst tube part 103 and the second tube part 104 are fixed together. Ascan be taken from FIG. 3, before the first tube part 103 is fixed to thesecond tube part 104, the dividing wall 110 may already be fixed (e.g.by welding) with its first edge 111 to the first surface section of thetube wall 101 and respectively of the first tube part 103. The dividingwall 110 is formed in such a way (with respect to its size andextension) that after the first tube part 103 is fixed (e.g. by welding)to the second tube part 104, the second edge 112 of the dividing wall110 resiliently abuts against the second surface section of the secondtube part 104.

Hence, an easy manufacturing method is achieved, because before thefirst tube part 103 is fixed to the second tube part 104, the dividingwall 110 can already be fixed with its first edge 111 and after thefirst tube part 103 is fixed to the second tube part 104 no furtherfixing steps are necessary.

It should be noted that the term “comprising” does not exclude otherelements or steps and “a” or “an” does not exclude a plurality. Alsoelements described in association with different embodiments may becombined. It should also be noted that reference signs in the claimsshould not be construed as limiting the scope of the claims.

1. A tube for being installed into a guide vane of a turbine, the tubecomprising: a tube wall for forming a fluid channel, and a dividing wallwhich is arranged inside the fluid channel, wherein the dividing wallcomprises a first edge and a second edge which is spaced apart from thefirst edge, wherein the first edge is fixed to a first surface sectionof the tube wall, and wherein the dividing wall is formed in such a waythat the second edge resiliently abuts in a detachable manner against asecond surface section of the tube wall such that the dividing walldivides the fluid channel in a first channel (I) and a second channel(II).
 2. The tube according to claim 1, wherein the first edge is weldedto the first surface section of the tube wall.
 3. The tube according toclaim 1, wherein the dividing wall is arranged inside the fluid channelin such a way that, if a first fluid pressure (p1) in the first channel(I) is higher than a second fluid pressure (p2) in the second channel(II), the second edge is pressed against the tube wall by the firstfluid pressure (p1).
 4. The tube according claim 1, wherein the firstsurface section has a first normal (n1), wherein the dividing wallcomprises a further first surface section which has a further firstnormal (fn1) and which comprises the first edge, wherein an angle (α)between the first normal (n1) of the first surface section and thefurther first normal (fn1) of the further first surface section differsfrom 90°.
 5. The tube according to claim 1, wherein the second surfacesection has a second normal (n2), wherein the dividing wall comprises afurther second surface section which as a further second normal (fn2)and which comprises the second edge, wherein the dividing wall is formedsuch that a further angle (β) between the second normal (n2) of thesecond surface section and the further second normal (fn2) of thefurther second surface section differs from 90°.
 6. The tube accordingto claim 1, wherein a centre axis runs between a first tube end and asecond tube end, wherein the tube is divided along a dividing directioninto a first tube part and a second tube part, and wherein the dividingdirection comprises at least a component which is parallel to the centreaxis.
 7. The tube according to claim 6, wherein the first tube part andthe second tube part are connected to each other by means of a weldingconnection.
 8. The tube according to claim 6, wherein the first edge ofthe diving wall is fixed to the first tube part, wherein the first tubepart comprises the first surface section, and wherein the second tubepart comprises the second surface section.
 9. The tube according toclaim 1, wherein the tube wall comprises holes for guiding a fluidbetween the fluid channel and the environment of the tube.
 10. A guidevane device for a turbine, the guide vane device comprising: a guidevane which comprises an inner volume, and a tube according to claim 1,wherein the tube is arranged inside the inner volume.
 11. A method ofmanufacturing a tube for a guide vane for a turbine, the methodcomprising: providing a tube which comprises a tube wall for forming afluid channel, fixing a first edge of a dividing wall to a first surfacesection of the tube wall, and resiliently abutting in a detachablemanner a second edge of the dividing wall, which second edge is spacedfrom the first edge, against the tube wall such that the dividing walldivides the fluid channel into a first channel (I) and a second channel(II).
 12. The method according to claim 11, wherein the tube has acentre axis which runs between a first tube end and a second tube end,and wherein the tube is divided along a dividing direction into a firsttube part and a second tube part, wherein the dividing directioncomprises at least a component which is parallel to the centre axis,wherein the fixing comprises fixing the first edge to the first tubepart, wherein the first tube part is fixed to the second tube part afterthe first edge is fixed to the first tube part, and wherein the abuttingcomprises resiliently abutting in a detachable manner the second edgeagainst the second tube part.